I think Gulliver has a greater perspective of civilization and self-understanding where both communities are wrapped up in their own concers. Whatever Gulliver did not gain in perspective (in terms of size) during his time in Lilliput, he gains in Brobdingnag. His time here not only gives Gulliver an understanding of what it is like to be powerless, but it also shows Gulliver how the Lilliputians must have felt when near him. Of course this situation is even more intimidating because here there are many giants, while in Lilliput he was the only one. This is how a Lilliputian would feel in England. The differences Gulliver experiences between the two islands are heightened because of the close proximity of the trips. Gulliver feels even smaller in Brobdingnag than he would have felt if he had never journeyed to Lilliput.
Gulliver's newfound understanding of perspective helps him to feel powerless more profoundly-first for himself, when he curls up and rather pathetically hopes to die, and then for others, especially for the Lilliputians he left behind. As his fear rises, he becomes more and more emotional, eventually becoming so overwhelmed that he gives up, curling up into the fetal position.